Knowledge Resource Center for Ecological Environment in Arid Area
| 增温对荒漠生物土壤结皮温室气体通量和净碳交换的影响 | |
| 其他题名 | Effects of warming on greenhouse gas fluxes and net ecosystem exchange of biological soil crusts in a desert region |
| 徐冰鑫 | |
| 出版年 | 2015 |
| 学位类型 | 硕士 |
| 导师 | 张志山 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 工业革命以来，大气中温室气体浓度持续上升导致全球平均气温明显升高，由此也引发了全球降水格局的改变。全球变暖背景下，主要温室气体（CO2、CH4和N2O）通量和生态系统净碳交换（NEE）的变化决定着温室气体和碳的源汇关系的转化以及对全球变暖的反馈方向和程度，因而倍受关注。因此，研究增温对CO2、CH4和N2O通量的影响以及增温和不同降水格局下的NEE变化对准确预估陆地生态系统对全球变化的响应具有重要的理论和实际意义。然而，目前针对荒漠生态系统的模拟增温研究较少，特别是对生物土壤结皮（BSCs）这一地表主要组成部分的研究更为少见。本文选择腾格里沙漠东南缘天然植被区的藻类、藓类以及二者混生的3种类型BSCs覆盖的土壤为研究对象，以开顶式生长室（OTC）为增温方式模拟全球变暖，通过3年连续观测增温（W）和不增温（NW）处理下BSCs的CO2、CH4和N2O通量以及研究W和NW处理3种降水格局下（递增降水、随机降水和递减降水）BSCs的光合（GEP）和生态系统呼吸（ER），为准确评估我国温带荒漠BSCs-土壤系统对全球变化的响应与反馈提供数据支撑。所取得的主要结果如下： （1）CO2和CH4通量主要受结皮类型的显著影响，不增温处理下藓类结皮的平均CO2通量和CH4通量分别为96.9和0.0228 mg?m–2?h–1，均显著高于藻类结皮和混生结皮。增温1.18℃分别降低了3类BSCs 2.38%~15%的CO2通量，却促进了藓类结皮CH4的排放和NO2的吸收。在季节尺度上，3类BSCs的CO2通量最大值均出现在6月或7月，夏季的CO2通量也均高于其他季节，而CH4和NO2通量没有明显的季节变化规律，增温仅对个别月份的温室气体通量影响显著。从年均通量来看，增温对BSCs的CO2、CH4、N2O通量和全球增温潜势（GWP）无显著影响。土壤温度和湿度与3种温室气体的关系随着BSCs类型的不同而异。5cm土壤温度与3类BSCs的CO2通量呈极显著指数正相关关系（p < 0.001），解释了14.6%~20.5%的CO2通量变化；土壤温度与混生结皮的CH4通量显著指数负相关，但仅解释了4%的CH4通量变化；土壤温度与N2O通量的无显著相关关系。10cm土壤湿度与3种BSCs的CO2通量呈极显著线性正相关（p < 0.001），解释了11.1%~15.3%的通量变化，与CH4和N2O通量之间的关系随BSCs类型的不同而呈负相关或不相关。此外，增温和不增温处理下的藻类结皮CO2和N2O通量差异与土壤湿度差异之间分别呈极显著正相关（p = 0.009）和负相关（p = 0.009）。以上结果表明，在全球变暖的背景下，荒漠BSCs-土壤系统主要温室气体通量不会有明显的变化，意味着荒漠生态系统温室气体的排放可能对气候变暖没有明显的反馈。 （2）增温与降水格局变化的互作决定藓类结皮的NEE和GEP的变化，降水格局变化显著影响藻类结皮的NEE、ER和GEP。W处理藓类结皮在递增降水时的GEP较NW处理显著降低65.3%；递增和随机降水时的NEE较NW处理显著增加56.8%和27.0%。NW处理下，藓类结皮递增降水的平均GEP比随机和递减降水显著高100%和84.2%，平均NEE比递减降水显著低35.2%；藻类结皮递增降水的平均GEP和ER比随机降水分别显著高73.2%和37.7%；W处理下两类BSCs 3种降水格局间的平均NEE、ER和GEP无显著差异。藓类结皮的累积NEE表现为CO2的源，均高于或显著高于藻类结皮。W处理下藓类结皮递增和随机降水的NEE累积量分别显著增加56.8%和27.0%，藻类结皮3种降水格局下的累积NEE均有所增加，但变化不显著。NW处理下藓类和藻类结皮递增降水的累积NEE比随机和递减降水分别显著低29.9%、31.0%和156、153%，而W处理下3种降水格局间均无显著差异。空气温度与藓类结皮的GEP、ER和NEE均呈极显著正指数相关关系（p < 0.001），与藻类结皮的GEP和ER呈显著正线性相关（p < 0.05）。土壤湿度与藓类结皮的GEP和ER呈极显著性正指数相关（p < 0.001），与藻类结皮的GEP和ER呈极显著性正线性相关（p < 0.001），与藻类结皮的NEE呈极显著性负线性相关（p < 0.001）。由此可见，气候变暖以及降水格局的变化会对荒漠BSCs-土壤系统的碳循环过程带来一定影响。 |
| 英文摘要 | Since the industry time, a continued rise of greenhouse gases concentration in the atmosphere caused a significant increase in average global temperature, which also led to changes in the pattern of global precipitation. At background of global warming, many attentions focused on changes in main greenhouse gases (CO2, CH4 and N2O) flux and net ecosystem exchange (NEE), both of which would have an important effect on the transformation of source and sink for carbon and greenhouse gases, and also determine the direction and extent of feedback to global warming. Therefore, it is meaningful to explore the effects of warming on CO2, CH4 and N2O flux and NEE under different precipitation patterns for accurate prediction about the responses of terrestrial ecosystems to global change. However, there is still lack of studies on changes in desert ecosystem responding to experimental warming to date, especially for the main part of surface components named biological soil crusts (BSCs) in these arid and semiarid region. In the thesis, open-top-chamber(OTC) was used to imitate climate warming, intact soil columns covered with three types of BSCs, including moss, algae and mixed crusts with moss and algae were collected at the southeast fringe of the Tengger Desert, and the fluxes of CO2, CH4 and N2O under warming (W) and non-warming (NW) treatment were measured during the period from June 2012 to December 2014. We also monitored photosynthesis (GEP) and ecosystem respiration (ER) of BSCs under W and NW treatment with three precipitation patterns (increasing, random and decreasing sequence). The aim was to provide evidences for a precise estimation on effect of BSCs & soil ecosystem in response to global change in the temperate desert region. The main results were as follows: 1. Fluxes of CO2 and CH4 were significant affected by BSCs types. Average fluxes of CO2 and CH4 of moss crust were 96.9 and 0.0228 mg?m–2?h–1, and significant higher than those of algae and mix crusts. Warming decreased CO2 flux of all three types of BSCs by 2.38%-15% based on 1.18℃ increase in soil temperature at 5 cm depth, but increased the emission of CH4 and absorption of NO2. At the seasonal scale, CO2 flux peaked in June or July and was higher in summar than other seasons, whereas no obvious tendency was found for seasonal dynamics of CH4 and N2O. Warming significantly affected the fluxes of greenhouse gases only in a few months. There were no significant differences of annual CO2, CH4 and N2O fluxes and global warmingpotentials (GWP) for three BSCs types between W and NW treatment. The relationships between soil temperature and moisture with greenhouse gases varied with BSCs types. CO2 flux of all BSCs types had a positively exponential relation with soil temperature at 5 cm depth (p < 0.001), which could explain 14.6%-20.5% of daily CO2 variation. CH4 flux of mix crusts had a negatively linear relation with soil temperature, which only explained 4% of daily CH4 variation. However, no significant relationship was found between N2O flux and soil temperature. A positively linear correlation between CO2 flux and soil moisture at 10 cm layer was found, which explained 11.1%-15.3% of daily CO2 variation. However, the relationships between CH4, N2O fluxs with soil moisture were negative or no significant, which depended on the types of BSCs. Moreover, the differences of CO2 and CH4 fluxes of algae crusts between W and NW treatment were positively (p = 0.009) or negatively (p = 0.009) correlated to the differences in soil moisture between two treatments. All results mentioned above suggest that the fluxes of greenhouse gases would not experience a significant change for the BSCs-soil system under global warming, meaning that the feedback of greenhouse gases in the desert ecosystem to climate warming would not be large in the future. 2. NEE and GEP of moss crusts were significantly affected by warming and interactions of warming and precipitation patterns, precipitation patterns also affected NEE, ER and GEP of algae crusts. In comparison with NW treament, warming decreased GEP of moss crusts under increasing precipitation by 65.3%, but significantly increased NEE by 56.8% and 27.0% under increasing and random precipitation, respecitively. Under NW treament, GEP of moss crusts under increasing precipitation were 100% and 84.2% higher than those under random and descreasing precipitation, but NEE was significantly lower than that under descreasing precipitation by 35.2%. GEP and ER of algae crusts under increasing precipitation were significantly higher than that for random precipitation by 73.2% and 37.7% under NW treament, respectively. But there were no significant differences in GEP, ER and NEE of the two types of BSCs between the rainfall patterns under W treament. Cumulative NEE of moss crusts was the source of CO2, which was higher or significantly higher than that of algae crusts, and increased significantly for increasing and random precipitation by 56.8% and 27.0%. It was also increased at three precipitation patterns for alage crusts under W treament but no significant difference was found. Cumulative NEE of moss and algae crusts for increasing precipitation pattern were significantly lower than those of random and descreasing precipitation patterns by 29.9%, 31.0% and 156, 153% under NW treament, respectively. However, there were on significant differences among three precipitation patterns under W treament. Air temperature was positively exponentially correlated to GEP, ER and NEE of moss crusts (p < 0.001), and positively linearily correlated to GEP and ER of algae crusts (p < 0.05). Soil mositure was positively exponentially correlated to GEP and ER of moss crusts and was also positively linearily correlated to GEP and ER, but negatively correlated to NEE of algae crusts (p < 0.001). Therefore, the climate warming and changes in rainfall patterns will affect the carbon cycle of BSCs-soil system. |
| 中文关键词 | 生物土壤结皮 ; 增温 ; 降水格局变化 ; 温室气体 ; 净碳交换 |
| 英文关键词 | Biological soil crusts Warming Change in precipitation pattern Greenhouse gases Net ecosystem exchange |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 生态学 |
| 来源机构 | 中国科学院西北生态环境资源研究院 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/287526 |
| 推荐引用方式 GB/T 7714 | 徐冰鑫. 增温对荒漠生物土壤结皮温室气体通量和净碳交换的影响[D]. 中国科学院大学,2015. |
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